This Power source can be used to power circuits or electronic devices that would normally use a 9 volt battery, saving us the cost of the battery while being used at home.

The half-wave rectifier rectification process.

Polarization of semiconductor diode in the forward and in the reverse direction. Input and output waveforms

This 12 VDC to -12 VDC converter circuit gives -12VDC (negative 12 volts) from a power source of + 12VDC (positive 12 volts), with very few components.